from fam_edge.qa import QAOrchestrator


class _FakeAdapter:
    def __init__(self, provider_name, chunks=None, raises=False):
        self.provider_name = provider_name
        self._chunks = chunks or []
        self._raises = raises

    def chat_stream(self, prompt, max_tokens=512):
        if self._raises:
            raise RuntimeError("boom")
        for c in self._chunks:
            yield c

    def chat(self, prompt, max_tokens=512):
        return ''.join(self._chunks) or None


def _orchestrator(adapters):
    qa = QAOrchestrator.__new__(QAOrchestrator)  # 跳过 __init__（不需要真实 config/adapters）
    qa.adapters = adapters
    return qa


def test_run_qa_stream_first_provider_success():
    qa = _orchestrator([_FakeAdapter("gemini", chunks=["你", "好"])])
    events = list(qa.run_qa_stream("hi"))
    types = [e["type"] for e in events]
    assert types == ["provider_trying", "chunk", "chunk", "done"]
    assert events[1]["text"] == "你"
    assert events[2]["text"] == "好"
    assert events[-1]["provider"] == "gemini"


def test_run_qa_stream_falls_back_when_first_yields_nothing():
    """核心诉求: 第一个 provider 一个字都没吐出来才允许换下一个——不是失败就切，
    是"完全没有产出"才切。"""
    qa = _orchestrator([
        _FakeAdapter("gemini", chunks=[]),
        _FakeAdapter("nvidia", chunks=["答案"]),
    ])
    events = list(qa.run_qa_stream("hi"))
    types = [e["type"] for e in events]
    assert types == ["provider_trying", "provider_failed", "provider_trying", "chunk", "done"]
    assert events[-1]["provider"] == "nvidia"


def test_run_qa_stream_does_not_switch_after_partial_output():
    """核心诉求: 已经开始吐字之后中途失败，不能悄悄换下一个 provider 接着写
    （会出现两段风格/内容不连贯的回答拼在一起）——直接结束这次生成。"""
    class _PartialThenRaise:
        provider_name = "gemini"
        def chat_stream(self, prompt, max_tokens=512):
            yield "先吐"
            raise RuntimeError("connection reset")

    qa = _orchestrator([_PartialThenRaise(), _FakeAdapter("nvidia", chunks=["不该被用到"])])
    events = list(qa.run_qa_stream("hi"))
    types = [e["type"] for e in events]
    assert types == ["provider_trying", "chunk", "done"]
    assert events[1]["text"] == "先吐"
    assert events[-1]["provider"] == "gemini"


def test_run_qa_stream_all_providers_fail():
    qa = _orchestrator([
        _FakeAdapter("gemini", chunks=[]),
        _FakeAdapter("nvidia", chunks=[], raises=True),
    ])
    events = list(qa.run_qa_stream("hi"))
    assert events[-1]["type"] == "all_failed"
    assert "provider_failed" in [e["type"] for e in events]


def test_run_qa_stream_exception_treated_as_no_output():
    qa = _orchestrator([_FakeAdapter("gemini", raises=True), _FakeAdapter("nvidia", chunks=["ok"])])
    events = list(qa.run_qa_stream("hi"))
    assert events[0] == {"type": "provider_trying", "provider": "gemini"}
    assert events[1] == {"type": "provider_failed", "provider": "gemini"}
    assert events[-1]["provider"] == "nvidia"